Conjugated Systems

requirements for aromaticity

1. cyclic

2. planar (no sp³ atoms)

3. conjugated (alternating single and double bonds)

4. number of π electrons (allylic lone pairs + double bond electrons) = 4n + 2

anti-aromatic

has 4n π electrons

bromination

chlorination

nitration

sulfonation

Friedel-Crafts alkylation

Friedel-Crafts acylation

Vilsmeier-Haack formylation

hydrogenation of aromatic pi bonds

Clemmensen reduction